The present invention relates to a carrier made of plastic for sealing a mold cavity in the manufacture of multi-component plastic part, a multi-component plastic part, and an apparatus and a method for producing a multi-component plastic part.
With the improvement of the external appearance of plastic parts, various methods have been developed to make the respective surfaces as visually appealing as possible. In particular, the SkinForm and ColorForm methods should be mentioned here, wherein plastic parts can be flooded with one or more components in a closed mold. In this way, multi-component plastic parts can be produced. Flooding is performed with a very low-viscosity material such as polyurethane or polyurea. Since these are one or more components of a low viscosity material, but are very fluid, the mold cavity in the mold, which is made of steel, cannot be sealed by using a steel carrier. The mold cavity must therefore always be sealed by a carrier made of plastic to ensure sufficient tightness. In addition, a sprue cavity and an overflow cavity must be provided when flooding of the plastic carrier, since air is unable to escape due to the good sealing properties of steel on plastic which normally occurs in conventional injection molding molds by way of the parting line. The air in the cavity—and possibly also flooding material—is thus forced into the so-called overflow cavity.
Due to the initially described procedure for the production of multi-component plastic parts, a border formed by the carrier material is thus always visible at the outer edge of the coated plastic parts. However, this is undesirable for many components. For these reasons, a pleat is often required, which cannot be implemented with conventional devices, since otherwise the parting line through the mold would be visible, which usually does not meet the quality requirements of the manufacturer and/or of the customers. As another disadvantage, the overflow cavity and the sprue cavity must usually be removed in a separate operation. In addition, areas separated by punching or laser ablation are always noticeable from the side and thus diminish the attainable quality of the finished multi-component plastic part.